LONDON – The reasons why fewer black than white patients undergo knee replacement as a treatment option for end-stage osteoarthritis remain elusive.
According to the findings of a 725-patient study, women and blacks with knee osteoarthritis (OA) were less willing than men or their white counterparts to consider having total knee replacement (TKR) surgery.
Black patients were also found to be less aware of the benefits of joint replacement and had worse expectations of the outcome than did white patients.
Despite a number of sociocultural differences, however, it is not clear why the uptake of TKR differs among ethnic groups.
"We know that joint replacement is an effective – actually the only effective – intervention for end-stage osteoarthritis," said study author Dr. C. Kent Kwoh, who is professor of medicine, epidemiology and clinical and translational science at the University of Pittsburgh and chief of the rheumatology section at VA Pittsburgh Healthcare System.
"The problem is that there have been many studies that have shown there are disparities in joint replacement; [blacks] get hip and knee replacement much less often than do whites," Dr. Kwoh added in an interview during a poster session at the annual European Congress of Rheumatology. "The question is, Why?"
Previous research has shown that even when faced with very severe and painful OA and a physician recommendation for TKR, black patients are less willing than whites to consider this an option.
The present study was in a much larger community-based sample than has been the case in past investigations, said Dr. Kwoh, and it aimed to identify more specific factors and patient attitudes that might influence the decision to undergo TKR.
Using a cross-sectional survey design, the investigators recruited patients aged 50 years or older who had chronic, frequent knee pain and radiographic evidence of OA.
The study population consisted of 234 black and 491 white patients, with mean respective ages of 58 years and 68 years (P less than .0004).
In addition to being younger, black patients tended to have worse knee pain, with higher total WOMAC (Western Ontario and McMaster Universities) osteoarthritis index scores (54 vs. 43), and OA Pain Assessment scores for constant (7 vs. 11) and intermittent (14 vs. 11) pain than white patients (P less than .0004 for all comparisons).
"There were differences in a number of [other] variables [between whites and blacks], such as income, employment status, education, access to insurance, expectations of outcome, trust in the health system, and religiosity, that may impact the choice for joint replacement" Dr. Kwoh observed.
However, putting all of these variables into a multivariate model didn’t seem to fully explain the disparity in TKR acceptance between the two groups.
The adjusted odds ratio for willingness to undergo TKR was 0.38 comparing black vs. white patients (95% confidence interval, 0.19-0.74; P = .005) and 2.52 for male vs. female sex (95% CI, 1.37-4.66; P = .003).
"We’re left a little bit puzzled at this point," Dr. Kwoh admitted. "Our other studies have shown differences in expectations; that is, if you have worse expectations, you were less likely to consider joint replacement."
In that previous work, however, an adjustment of the findings according to patient expectations seemed to take care of the difference in willingness. "In this study, we weren’t able to show that," Dr. Kwoh said. "So maybe there are other, unmeasured confounders that we have to address."
As to where these findings leave the practicing physician who advises patients, Dr. Kwoh noted that patient education is important and that patients really need to have a good understanding of the risks and benefits.
"Joint replacement is effective, we know that it works very well, it has low morbidity and low mortality, and so patients who really need it should avail themselves to it," Dr. Kwoh advised.
Dr. Kwoh stated that he had no conflicts of interest. The study was funded by the University of Pittsburgh Multidisciplinary Clinical Research Center for Rheumatic and Musculoskeletal Diseases.